[VBLOCKS-1973] Fix: show busy during login and register

[kpchoy]

Submission Checklist

• [ ] The CHANGELOG.md reflects any feature, bug fixes, or known issues made in the source code
• [ ] New unit tests and integration tests have beed added
• [x] Code coverage is more or equal to the previous coverage
• [x] A visual inspection of the Files changed tab was made prior to submitting the pull request ensuring the style guide was followed
• [ ] CI pipeline is green
• [ ] Included screenshot if necessary

Description

VBLOCKS-1973

Breakdown

• Add Slice for LoginAndRegister asyncThunk
• Allows us to show busy UI for login, getAccessToken and register steps

Validation

• local testing

Additional Notes

[Any additional comments, notes, or information relevant to reviewers.]

Contributing to Twilio

All third-party contributors acknowledge that any contributions they provide will be made under the same open-source license that the open-source project is provided under.

• [x] I acknowledge that all my contributions will be made under the project's license.